<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style> 
        *{
            margin: 0;
            padding: 0;
            box-sizing: border-box;
        }
        body{
            background-color: pink;
        }
        .box{
            width: 100px;
            height: 100px;
            background-color: red;
            margin: 300px auto;
            position: relative;
            transform: rotate(45deg);
            box-shadow: 0 0 50px 0 red;
            animation: heart 0.5s alternate infinite;
        }
        .box::before{
            content: "";
            width: 100px;
            height: 50px;
            background-color: red;
            border-radius: 100px 100px 0 0;
            position: absolute;
            top: -49px;
            left: 0;
            box-shadow: 0 0 50px 0 red;
        }
        .box::after{
            content: "";
            width: 50px;
            height: 100px;
            background-color: red;
            border-radius: 100px  0 0 100px;
            position: absolute;
            top: 0;
            left: -49px;
            box-shadow: 0 0 50px 0 red;
        }
        @keyframes heart{
            0%{
                transform: rotate(45deg) scale(1);
            }
            100%{
                transform: rotate(45deg) scale(1.5);
            }
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>